Process of bleaching cane.



'No. 722,869. "PATENTED MARJ17Q1903. H. 0. MEYERK; E. B-ESENBRUCHLPROCESS OF BLEAGHING CANE.

APPLICATION FILED JUNE 20, 1898.

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ATI-ORAE YS' UNITED STATES PATENT FFICE.

HEINRICH CHRISTIAN MEYER AND ERNST BESENBRUCH, OE HARBURG-ON- THE-ELISE,GERMANY, ASSIGNORS TO THE FIRM OF H. C. MEYER, JR., OFHARBURG-ON-THE-ELBE, GERMANY;

PROCESS OF :BLE'ACHI NG CANE.

SPECIFICATION forming part of Letters Patent No. 722,869, dated March17, 1903. Application filed June 20,1898: Serial No. 683,978. (Nospecimens.)

To aZZ whom itmrtyconcernq I Be it known that we, HEINRICH CHRISTIANMEYER and ERNST BESENBRUCH, subjects of the German Emperor, residing atHarburgon-the-Elbe, German Empire, have invented an Improved Process ofBleaching and Dyeing Glazed or Smooth Cane, (Case No. 1,) of

- which the following is a full, clear, concise, and exact description.

Our invention relates to an improved process for treating and bleachingnatural or nondesilicified cane, and has for its object the provision ofa method for treating cane without affecting the silicious or silicifiedcoats or layers thereof.

By following the process herein outlined different varieties of cane ofvarious natural shades may be treated and subsequently bleached toproduce a commercial article which, in addition to being uniform incolor,

retains the cane otherwise in its natural condition. A V In making canechairs and the like it has become customary for some time to dye the z 5cane employed, in order to thereby obtain special artistic effects. As,however, the natural cane is variously colored, it must be bleachedbefore being dyed, at least with the exception of the very clearestsorts.- In the natural Bengal or ratan cane three diiferent layersexist-namely, first, the inner core, the so-called pith, consisting ofwoody substances; secondly, a layer only partially composed of organicsubstance and strongly im- 3 5 pregnated with silicic acid, the socalled bast or bark,and, finally, asmooth polished or glazed outercourse composed almost exclusively of pure silicic acid. Seeing that inthebleachingof the caneit has been found that the outer layer of silica,as well as the bast, which is thoroughly permeated with silicic acid ina natural condition, are practi cally unattackable in thebleaching-bath, the conclusion was arrived at'that in the manu- 5facture of colored goods the treatment must always commence with thecomplete removal of the silicic acid. The removal of the silicic acid inthe processes hitherto employed must be regarded as a necessary evil,not only because it offers great technical difficulties, but,

above all things, because the layer of silica must be regarded as a'very valuable constituent of the cane, as owing to its fine naturalpolish and its capability of resisting almost all chemical andmechanical influences it adds not inconsiderably to the beauty anddurability of the cane. While, therefore, the process of treatmenthitherto adopted for the cane has been limited, after the removal of thelayer of silica, to bleaching superficially the layer of best lyingimmediately beneath the same, the inventors of the present process haveendeavored to leave the natural layer of silica unattacked or unaffectedand to produce thebleaching and dyeing in such away that the wholethickness of the layer of bast lying beneath it is entirely bleached anddyed through, which was hitherto regarded as impossible. The measuresadopted for this must be varied according to whether'it is a question ofmaking the so-called weaving-cane--that is to say, themechanicallydrawn-oflf upper layer of the cane or rodor of treating thenatural raw product. Even in the latter case it is not difiicult tobring the bleaching liquid from the interior in contact with the layerof bast, because the Bengal cane, as is well known, is longitudinallyextremely'porous and may be comparatively easily filled with liquid withthe use of slight pressure. If, however, this process is followed, theresult is that the upper layers, which are permeated with silicic acid,are not attacked by the bleaching substance. If the bleaching process becontinued long enough,a thorough bleaching can be obtained; but as thebleaching fluid exerts a disintegrating action on the fibers those partsof the woody fiber in which the bleaching action hasalready started atthe commencement of go the operation are entirely decomposed when thetreatment is continued for too longa period. The bleaching must thus becarried on for a given time, and therefore care must be taken that ableaching action may be exerted simultaneously on all parts of the canefrom the start of the operation. For this object we employ variousmeans. Sometimes the cane is brought in closed vessels into thebleaching-bath and exposed to great variaroo B. The cane which is to betreated having been placed within the chamber, the bleach ing or otherfluid is forced into the kettle through valve C, and the contents of thekettle are subjected to any desired pressure. Upon the cover are mounteda pressure-gage D, an air-cock E, and a safety-valve F. Situated at theside of the kettle is a cock G, which is designed for drawingoif sampleportions of the liquid for the purpose of testing the same. apparatusfor heating the contents may be employed in connection with the devicefor securing the desired temperature. As, however, the layer of bastpermeated with silicic acid is very slightly permeable in a transversedirection, it has been found to be preferable to subject the cane to achemical treatment in addition to the mechanical treatment by variationsof pressure, the object of the chemical treatment being to open thepores of the cane in such a way that they allow free access to thesubsequent bleaching. For this object a treatment with alkalinesolutions, preferably solutions of potash compounds, has been foundparticularly suitable; but care must be taken that the concentrationsand temperatures of these solutions are not made so great thata solutionof the layer of silica itself takes place. If, for artistic reasons, itbe desired to obtain intentionally a dull surface, the layer of silicamay be easily attacked to any desired degree by a suitable raising ofthe temperatures or the concentrations in the preliminary treatment.

We have found the following methods of treatment to be particularlysatisfactory in preparing cane for the purpose of bleaching and dyeingthe same. Asolution of potassic hydrate ranging in strength from six toten per cent., applied cold, is permitted to act upon the cane fromtwelve to twenty-four hours. It may frequently be found advantageous,however, to employ this solution at a temperature of about sixtydegrees. We have also used a ten to fifty per cent. solution of silicateof potash, which is maintained at approximately sixty degrees and isallowed to act upon the treated cane from two to twenty-four hours.After treating the cane as above indicated the same is subjected to anysuitable bleaching-bath. This may, forexample, consist of potassic hypochlorite, the bleaching being conducted in a manner well known tothose skilled in the art. If desired, the alkaline and bleachingreagents may also frequently be employed in a single bath with goodresults. If so-called weaving-cane is to be made by the present process,it is preferable to first split the cane and then subject it to theabove-mentioned preliminary treat- Steam-coils or other well-known ment,in which case a mechanical treatment by variations of pressure may beentirely dispensed with. Said alkaline solutions may also be addeddirectly to the bleaching-bath.

We have found that the treatment of Bengal cane with alkalinesolutionshas already been described, with the object of removing the silica. Thisprocess, as is well known, hasnot been worked practically, mainly fortwo reasons: First, the energetic treatment with soda necessary forremoving the silica had a deleteriousaction on the mechanical propertiesof the fibers, and, secondly, any alkaline treatment produced a strongbrown coloring of the cane, which in the bleaching processes hithertoemployed could not be entirely removed, but imparted a yellowish effectto the subsequent dyeing, which did not produce readily marketable cane.If the bleaching was then further continued, the color of the cane tookon a grayish tone, which was also undesirable. We have found that, onthe one hand,.a treatment with cold or moderately-heated weak alkali,which is necessary in order to open the pores, does not appreciablyalfect the mechanical properties of the cane, and, on the other hand,the formation of the undesirable so-called yolk-ofegg color is to be.ascribed to an unequal bleaching of the difierent layers, as the layerlying under the surface is essentially-more slowly attacked than theother layers. If, however, on the other hand, care be taken, as isintended in the present process, that the bleaching liquid from thestart can simultaneously attack all layers of the cane, a correspondingcomplete and even bleaching through is obtained, and the formation ofthe yolk-of-egg color is avoided. We have also observed that in the useof potash compounds instead of the soda hitherto employed in thealkaline removal of the silica the deleterious yolk-of-egg color did notarise to the same extent, although at first a material darkening orbrowning of the cane was observable. By the means hereinbefore describedthe possibility is thus afiorded, which was hitherto not recognized, ofcompletely bleaching through the desilicated cane, and a new technicaleffect is thereby produced, in that any sort of cane of no matter howdark a natural color "may be bleached through to the same degree ofclearness, so that any subsequent sorting may be entirely dispensedwith.

Having now described processes which we preferably practice forbleaching and dyeing glazed cane, we claim as new, together with suchmodifications as may be made by those versed in the art, the following:

1. The herein-described process for bleaching natural ornon-desilicified cane, which consists in treating the same with analkaline fluid whose concentration and temperature are adapted to retainor preserve the silicious layer of the cane, and thereafter treatingsaid cane in a bleaching-bath. I

2. The herein-described process for bleach- IIO ing natural ornon-desilicified cane, which consists in treating the cane with asolution of postash-lye, the concentration and temperature of which areso regulated that the silicious layer of the cane is preserved, andthereafter subjecting said cane to the action of a bleaching fluid.

3. The herein-described process of treating natural or non-desilicifiedcane, which consists in placing the cane in a solution containing fromsix to ten per cent. of potassium hydroxid, the same being maintained ata normal temperature, and thereafter subjecting the cane to the actionof a bleaching-bath.

4. A process for bleaching natural or nondesilicified cane, whichconsists in subjecting the treated cane to solutions containing a lowpercentage of alkali which do not ma- Ierially afiect the siliciouscoating or layer of the cane and which permit the entrance of thebleaching solution into the pores of the cane and thereafter treatingwith a bleaching solution, substantially as described.

5. A process for bleaching natural or nondesilicified cane, whichconsists in subjectingthe cane toa weak alkaline solution adapted tomaintain the silicious coating of the cane intact, and to a bleachingagent which is thereby adapted to fill the pores and act upon thedarkened portions of the cane, substantially as described.

6. The process of bleaching cane in a natural or non-desilicified state,which consists in treating the said cane under varying pressure with apotassium salt in solution, the strength of which is from six to ten percent., whereby the silicious layer of the cane is unattacked andretained, and thereafter exposing the cane to the action of ableaching-bath, substantially as described.

7. A process for bleaching natural or nondesilicified cane, whichconsists in subjecting the treated cane to a solution containing a lowpercentage of potassium hydrate of normal or moderate temperature whichdoes not materially affect the silicious coating or, layer of the caneand which permits the entrance of the bleaching solution into the poresof the cane, substantially as described.

8. The process of bleaching cane, which consists in subjecting the caneto a penetrating reagent that will not effect the removal of thesilicious coating, nor the disintegration of the fibers of the cane, andwhich will open the pores of the cane to permit of access of a bleachingreagent, and passing a bleaching reagent, that will not 'efiect theremoval of the silicious coating nor the disintegration of the fibers ofthe cane, through the opened pores, whereby all portions of the cane arespeedily reached by the bleaching reagent substantially as described.

9. The herein-described process of preparing cane which consists intreating the same so as to open the pores thereof, and subjecting saidcane to the action of a bleaching fluid.

In witness whereof we have hereunto subscribed our names this 3d day ofJune, A. D. 1898.

HEINRICH CHRISTIAN MEYER. ERNST BESENBRUCH.

Witnesses MAX WAGNER, GERTRUD VENTSCH.

